To elaborate, Soujiro totally bought into Shishio (an unhealthy 8w7)'s philosophy of might makes right. And he seemed to have very little conscience. People idealize this character a lot, pointing out that he leaves Shishio after he loses to Kenshin. But who's to say that means all of a sudden Soujiro is a kind, principled person? Not me.
As for Kenshin, I can kinda see him as a 9, but the wing is iffy to me. I don't separate Hitokiri Battousai from Himura Kenshin; they're one in the same. Kenshin sure killed a lot of people for a 9w1. In the anime series, Kenshin is all light and fluffy at times. In the manga he has an easygoing personality most of the time but it's not as pronounced.